In general, in a wireless personal area network (WPAN), a beacon, which indicates network status information, is periodically transmitted to the whole or a part of the network in order to transmit network status of the WPAN or status of a predetermined device with another device in the WPAN. In a centralized beaconing scheme, a predetermined device that is defined in advance mainly transmits a beacon that manages the whole network. In a distributed beaconing scheme, all devices in the network transmit beacons. An example of the centralized beaconing scheme is the IEEE 802.15 based WPAN system, and an example of the distributed beaconing scheme is the Wimedia system based on ECMA-386 standards.
FIG. 1 is a schematic view of an example of a conventional centralized beaconing scheme, and FIG. 2 is a schematic view of an example of a conventional distributed beaconing scheme.
Referring to FIG. 1, in the conventional centralized beaconing scheme, a predetermined device that is defined in advance transmits a beacon that manages the whole network; here, a superframe 100 is divided into a beacon period section 110 and a data/control signal section 120, and a beacon B in the beacon period section 110 is transmitted by the predetermined device, that is, a network coordinator and other devices are conformably operated by a command of a beacon received by the network coordinator.
Referring to FIG. 2, in the conventional distributed beaconing scheme, all devices in a network transmit a beacon; that is, all devices sequentially transmit a beacon via a beacon period BP 160 to inform a network status thereof to other devices and also receive network status information of the other devices. In FIG. 2, for example, three devices transmit beacons 162, 164, and 166, respectively.
In the conventional distributed beaconing scheme, all devices transmit a beacon by turns. However, if the number of devices is increased, information may be repetitively transmitted, and a beacon period also is increased, which reduces data transmission time and thus reduces the total transmission efficiency. On the other hand, in the conventional centralized beaconing scheme in which only a predetermined device transmits a beacon, if there is a small number of devices, a hidden node is generated in a coverage in which each of the devices is included and thus it is difficult to efficiently control the network.